From 422c64294937753ce47a737eec62eded76cf80b2 Mon Sep 17 00:00:00 2001
From: decentral1se <cellarspoon@riseup.net>
Date: Wed, 4 Oct 2023 03:24:30 +0200
Subject: [PATCH] fix: ensure ipv4 is checked, not sometimes ipv6

See https://git.coopcloud.tech/coop-cloud/organising/issues/490
---
 pkg/dns/dns.go      |  7 ++++++-
 pkg/dns/dns_test.go | 32 +++++++++++++++++++++++++++++---
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/pkg/dns/dns.go b/pkg/dns/dns.go
index 4c888a3f..46408049 100644
--- a/pkg/dns/dns.go
+++ b/pkg/dns/dns.go
@@ -7,11 +7,16 @@ import (
 
 // EnsureIPv4 ensures that an ipv4 address is set for a domain name
 func EnsureIPv4(domainName string) (string, error) {
-	ipv4, err := net.ResolveIPAddr("ip", domainName)
+	ipv4, err := net.ResolveIPAddr("ip4", domainName)
 	if err != nil {
 		return "", err
 	}
 
+	// NOTE(d1): e.g. when there is only an ipv6 record available
+	if ipv4 == nil {
+		return "", fmt.Errorf("unable to resolve ipv4 address for %s", domainName)
+	}
+
 	return ipv4.String(), nil
 }
 
diff --git a/pkg/dns/dns_test.go b/pkg/dns/dns_test.go
index 49b414fd..99249a71 100644
--- a/pkg/dns/dns_test.go
+++ b/pkg/dns/dns_test.go
@@ -3,6 +3,8 @@ package dns
 import (
 	"fmt"
 	"testing"
+
+	"gotest.tools/v3/assert"
 )
 
 func TestEnsureDomainsResolveSameIPv4(t *testing.T) {
@@ -11,9 +13,10 @@ func TestEnsureDomainsResolveSameIPv4(t *testing.T) {
 		serverName     string
 		shouldValidate bool
 	}{
-		// NOTE(d1): DNS records get checked, so use something we control. if
-		// you're here because of a failing test, try `dig +short <domain>` to
-		// ensure stuff matches first!
+		// NOTE(d1): DNS records get checked, so use something that is maintained
+		// within the federation. if you're here because of a failing test, try
+		// `dig +short <domain>` to ensure stuff matches first! If flakyness
+		// becomes an issue we can look into mocking
 		{"docs.coopcloud.tech", "coopcloud.tech", true},
 		{"docs.coopcloud.tech", "swarm.autonomic.zone", true},
 
@@ -36,3 +39,26 @@ func TestEnsureDomainsResolveSameIPv4(t *testing.T) {
 		}
 	}
 }
+
+func TestEnsureIpv4(t *testing.T) {
+	// NOTE(d1): DNS records get checked, so use something that is maintained
+	// within the federation. if you're here because of a failing test, try `dig
+	// +short <domain>` to ensure stuff matches first! If flakyness becomes an
+	// issue we can look into mocking
+	domainName := "collabora.ostrom.collective.tools"
+	serverName := "ostrom.collective.tools"
+
+	for i := 0; i < 15; i++ {
+		domainIpv4, err := EnsureIPv4(domainName)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		serverIpv4, err := EnsureIPv4(serverName)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		assert.Equal(t, domainIpv4, serverIpv4)
+	}
+}